Multispectral quantitative MR imaging of the human brain: lifetime age-related effects

Quantitative magnetic resonance (MR) imaging allows visualization of age-related changes in the normal human brain from functional, biochemical, and morphologic perspectives. Findings at quantitative MR imaging support age-related microstructural changes in the brain: (a) volume expansion, increased myelination, and axonal growth, which establish neural connectivity in neurodevelopment, followed by (b) volume loss, myelin breakdown, and axonal degradation, leading to the disruption of neural integrity later in life. A rapid growth change followed by a continuous slower change in quantitative MR parameters can be modeled with a logarithmic or exponential decay function. The age dependencies during adulthood often fit a quadratic model for transitional changes with accelerated aging effects or a linear model for steady changes.Understanding these general trends over the human life span can improve assessment for a specific disease by helping determine appropriate study settings. Once a consensus on acquisition techniques and image processing algorithms has been reached, quantitative MR imaging can play an important role in the assessment of disease states affecting the brain.